1. Field of the Invention:
This invention pertains to the field of automobile tow trucks. In particular, this invention concerns towing bed, tilt bed, and slide-back carriers adapted for use on one- or two-ton trucks.
2. Description of the Prior Art:
Tow trucks comprised of flat bed trailers or flat bed one-ton type trucks are common in the prior art. In tow trucks of this type, the flat bed is movably mounted to the truck frame to allow the bed to be moved from a carrying position to a loading position. In the former configuration, the bed and its payload, an automobile, are situated substantially on the vehicle frame so that the center of gravity of the bed and automobile fall between the vehicle axles. In the loading position, the bed is typically projected rearward from the back of the vehicle frame and tilted downward into contact with the ground to form a ramp. The vehicle is then pulled onto the bed by a winch. Once the automobile is tied down, the bed is returned to the carrying position.
The slide-back flat bed carriers are designed to perform this function by, first, elevating the front of the bed and then, second, sliding the bed back until the rear edge of the bed contacts the ground. The 17 foot Aluminum Weight Watcher sold by Fazekas Industries is typical of the slide-back carriers employing slide beams that are tilted into position and upon which the flat bed slides. Tow trucks manufactured by Landoll Corporation ("Loadoll I"), Brimec, Century Wrecker Corporation, Jerr-Dan Corporation ("Wrangler"), and Aatac, Inc., advertised and described in the trade magazines American Towman, Vol. 9, No. 7, 1986, Dec., 1986, and TowTimes, Vol. 4, No. 6, Jan., 1987, for example, are of similar design.
In one or two-ton slide-back carriers the angle at which the bed contacts the ground --i.e. the loading or approach angle - is typically 10-15 degrees. For lower loading angles, a semi or tractor-trailer rig is required since a lower anqle requires in the prior art. a longer bed. The length of bed necessary to qenerate a sub 10 degree loading angle is too long for even the largest 1 or 2 ton truck. Flat bed trailers such as the "Model TK705A" by Trail King Industries, Inc., can achieve a loading angle approaching 7 degrees. Use of optional ramps can produce a 5 degree angle, such as the "Hydra-Trail" of Ledwell and Sons.
Shallow loading angles are required to achieve front and rear end clearance as the automobile is hoisted onto the flat-bed. In late model year cars, these clearances are smaller, thus shallower loading angels are required. These shallower angles are well below the capability of the one-ton or two-ton slideback carrier trucks of the prior art. Resort to a trailer to serve as a tow truck is both cumbersome and expenslve. The use of additional ramps is equally cumbersome.